:root {
    --las-primary: #2563eb;
    --las-primary-dark: #1d4ed8;
    --las-bg: #f8fafc;
}

body {
    background: var(--las-bg);
    font-size: 1.05rem;
    min-height: 100vh;
}

.app-header {
    background: linear-gradient(135deg, var(--las-primary), var(--las-primary-dark));
    color: #fff;
}

.app-brand {
    color: #fff;
    font-size: 1.5rem;
    font-weight: 700;
}

.user-badge {
    font-size: 1.1rem;
    opacity: 0.95;
}

.login-card {
    border: none;
    border-radius: 1rem;
}

.info-card,
.placeholder-card,
.welcome-panel {
    background: #fff;
    border-radius: 1rem;
    padding: 1.5rem;
    box-shadow: 0 0.25rem 1rem rgba(15, 23, 42, 0.06);
}

.placeholder-card {
    min-height: 120px;
    border: 2px dashed #e2e8f0;
    box-shadow: none;
}

.btn-lg {
    padding: 0.75rem 1.25rem;
    font-size: 1.15rem;
}

.form-control-lg {
    font-size: 1.15rem;
    padding: 0.75rem 1rem;
}

@media (min-width: 768px) {
    body {
        font-size: 1.125rem;
    }

    .app-brand {
        font-size: 1.75rem;
    }
}

/* Materials list */
.material-card {
    background: #fff;
    border-radius: 1rem;
    padding: 1.5rem;
    box-shadow: 0 0.25rem 1rem rgba(15, 23, 42, 0.06);
}

.difficulty-badge {
    font-size: 0.95rem;
    padding: 0.4em 0.75em;
}

.difficulty-basic {
    background-color: #dcfce7;
    color: #166534;
}

.difficulty-extended {
    background-color: #dbeafe;
    color: #1e40af;
}

.difficulty-challenge {
    background-color: #fef3c7;
    color: #92400e;
}

.entry-card {
    display: block;
    background: #fff;
    border-radius: 1rem;
    padding: 1.5rem;
    box-shadow: 0 0.25rem 1rem rgba(15, 23, 42, 0.06);
    border: 2px solid #dbeafe;
    transition: border-color 0.15s, box-shadow 0.15s;
}

.entry-card:hover {
    border-color: var(--las-primary);
    box-shadow: 0 0.5rem 1.25rem rgba(37, 99, 235, 0.12);
}

/* Material detail / reading */
.article-panel {
    background: #fff;
    border-radius: 1rem;
    padding: 1.75rem;
    box-shadow: 0 0.25rem 1rem rgba(15, 23, 42, 0.06);
}

.article-title {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 1.25rem;
}

.article-content {
    font-size: 1.125rem;
    line-height: 1.9;
    white-space: pre-wrap;
    color: #1e293b;
}

.phase-notice {
    background: #eff6ff;
    border: 1px solid #bfdbfe;
    border-radius: 0.75rem;
    padding: 1rem 1.25rem;
    font-size: 1.05rem;
    color: #1e40af;
}

.question-card {
    background: #fff;
    border-radius: 1rem;
    padding: 1.5rem;
    box-shadow: 0 0.25rem 1rem rgba(15, 23, 42, 0.06);
}

.question-no {
    font-weight: 700;
    font-size: 1.15rem;
}

.question-text {
    font-size: 1.125rem;
    line-height: 1.7;
    margin-bottom: 1.25rem;
}

.options-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.option-btn {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: #f8fafc;
    border: 2px solid #e2e8f0;
    border-radius: 0.75rem;
    font-size: 1.05rem;
    line-height: 1.5;
    cursor: default;
}

.option-key {
    flex-shrink: 0;
    width: 2rem;
    height: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #fff;
    border: 2px solid #cbd5e1;
    border-radius: 50%;
    font-weight: 700;
}

.option-text {
    flex: 1;
    padding-top: 0.15rem;
}

@media (min-width: 768px) {
    .article-content {
        font-size: 1.2rem;
    }

    .question-text {
        font-size: 1.2rem;
    }

    .option-btn {
        font-size: 1.125rem;
    }
}

/* Navigation */
.nav-link-light {
    color: rgba(255, 255, 255, 0.9);
    text-decoration: none;
    font-size: 1.05rem;
    font-weight: 500;
}

.nav-link-light:hover {
    color: #fff;
    text-decoration: underline;
}

/* Start practice */
.start-practice-panel {
    background: #fff;
    border-radius: 1rem;
    padding: 1.5rem;
    box-shadow: 0 0.25rem 1rem rgba(15, 23, 42, 0.06);
}

/* Attempt answer page */
.option-selectable {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: #f8fafc;
    border: 2px solid #e2e8f0;
    border-radius: 0.75rem;
    font-size: 1.1rem;
    line-height: 1.5;
    cursor: pointer;
    margin: 0;
    transition: border-color 0.15s, background 0.15s;
}

.option-selectable:hover {
    border-color: #93c5fd;
    background: #eff6ff;
}

.option-selectable:has(.option-input:checked) {
    border-color: var(--las-primary);
    background: #eff6ff;
}

.option-input {
    flex-shrink: 0;
    width: 1.35rem;
    height: 1.35rem;
    margin-top: 0.35rem;
    cursor: pointer;
}

.submit-bar {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.95);
    border-top: 1px solid #e2e8f0;
    box-shadow: 0 -0.25rem 1rem rgba(15, 23, 42, 0.08);
    z-index: 100;
}

/* Result page */
.result-summary {
    background: #fff;
    border-radius: 1rem;
    padding: 1.75rem;
    box-shadow: 0 0.25rem 1rem rgba(15, 23, 42, 0.06);
}

.result-stat-card {
    background: #f8fafc;
    border-radius: 0.75rem;
    padding: 1.25rem;
    text-align: center;
    height: 100%;
}

.result-stat-label {
    color: #64748b;
    font-size: 1rem;
    margin-bottom: 0.5rem;
}

.result-score {
    font-size: 3rem;
    font-weight: 800;
    color: var(--las-primary);
    line-height: 1;
}

.result-stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: #1e293b;
}

.question-correct {
    border-left: 4px solid #22c55e;
}

.question-wrong {
    border-left: 4px solid #ef4444;
}

.answer-detail {
    background: #f8fafc;
    border-radius: 0.75rem;
    padding: 1rem 1.25rem;
    font-size: 1.05rem;
    line-height: 1.7;
}

/* Attempts history */
.attempts-table {
    background: #fff;
    border-radius: 1rem;
    overflow: hidden;
    box-shadow: 0 0.25rem 1rem rgba(15, 23, 42, 0.06);
}

.attempts-table thead th {
    background: #f8fafc;
    font-size: 1rem;
    white-space: nowrap;
}

.attempts-table td {
    font-size: 1.05rem;
}

@media (min-width: 768px) {
    .option-selectable {
        font-size: 1.2rem;
        padding: 1.15rem 1.5rem;
    }

    .option-input {
        width: 1.5rem;
        height: 1.5rem;
    }
}